diff --git a/src/gui/water_quality_gui_v2.py b/src/gui/water_quality_gui_v2.py
index 7c30353..bd7fac0 100644
--- a/src/gui/water_quality_gui_v2.py
+++ b/src/gui/water_quality_gui_v2.py
@@ -395,8 +395,9 @@ class WaterQualityGUI(QMainWindow):
 
             # 分隔符 (不需要实体占用高度，缩小即可)
             if stage_idx < len(stage_names) - 1:
+                from PyQt5.QtCore import QSize  # 正确引入 QSize
                 sep = QListWidgetItem("")
-                sep.setSizeHint(sep.sizeHint().expandedTo(Qt.QSize(0, 5)))
+                sep.setSizeHint(QSize(0, 10))   # 直接使用 QSize
                 sep.setFlags(sep.flags() & ~Qt.ItemIsSelectable & ~Qt.ItemIsEnabled)
                 self._step_list.addItem(sep)